Content retrieving device and content retrieving method

ABSTRACT

A multimedia content retrieving device for retrieving multimedia content stored in a terminal through a network includes a memory that stores a terminal ID of a managing terminal that stores meta information. The meta information includes information relating to the multimedia content including a content ID and a terminal ID of a terminal that stores the content. A the multimedia content retrieving device also includes a retrieving device that inputs a retrieving condition that specifies information relating to the content, an obtaining device that obtains the meta information, a specifying device that specifies the content ID based on the meta information obtained by the obtaining device, and the terminal ID of the terminal storing the content, and a transmitting device that transmits a request for obtaining the content relating to the content ID through the network to the terminal specified by the specifying device.

CROSS-REFERENCE TO RELATED APPLICATIONS

Priority under 35 U.S.C. § 119 is claimed to Japanese Patent ApplicationNo. 2003-202464, filed on Jul. 28, 2003, the disclosure of which isincorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a multimedia content retrieving deviceand a multimedia content retrieving method for retrieving content storedin a terminal.

2. Discussion of the Background

There is a technique for connecting a terminal such as a personalcomputer (hereinafter called a PC), a portable telephone, a portableterminal such as a PDA (Personal Digital Assistance), or an informationterminal such as a TV with a program recorder, etc. to a server by awired or wireless network, and transferring multimedia content data(hereinafter called content) such as video, music and still images tothe terminal via the server. Thus, this technique allows the contentsuch as a program, a photograph, music, etc. to be audio-visualizedirrespective of location.

A home server is an example of a server that may be used to provide sucha function, and includes a large capacity storage device such as a HDD,or a DVD, etc. and accumulates and manages the content.

The home server controls and manages a terminal device connected to anetwork constituting a home network.

For example, content such as video or music stored within the homeserver can be transferred to a PC located in a study, a kitchen and abedroom using wired or wireless communication by arranging the homeserver in a sitting room, for example, with a wired or wireless LANfunction.

Further, the home server has the role of, so to speak, a control towerfor accumulating content and transmitting and receiving content to andfrom terminals located within the home.

Further, the home server has a function for retrieving and displayingpredetermined desirable content among the content accumulated in amemory medium within the terminal connected to the network and a memorymedium within the home server.

Meta information describing additional information related to thecontent is managed by the home server to manage the content accumulatedin the memory media and the terminal.

Here, there is a possibility that the amount of meta information formanaging the content within each terminal connected by the network maybecome very large.

As the functions of devices such as digital cameras and portabletelephones with camera functions are improved, increased amounts ofdigital photographs can be stored daily on the home server or the PCterminal.

For example, each member of a family may have a portable telephone witha camera function, and all managing information (i.e., meta information)related to the resulting photo content is managed by the home server. Inthis case, all the meta information relating to that content isregistered and managed within the home server. The home server mustupdate pertinent meta information every time content is added, moved,deleted or copied within the terminal connected by the network orbetween the terminals. Therefore, there is a problem of an increase inthe processing amount of the server.

SUMMARY OF THE INVENTION

Accordingly, one object of the present invention is to provide a novelcontent retrieving device and a novel content retrieving method able toefficiently manage the meta information related to the content stored ona terminal in the network and to retrieve the content.

Further, another object of the present invention is to provide a novelprogram for making a computer execute a procedure corresponding to thenovel content retrieving device and method, and to provide a novelcomputer readable recording medium and recording this program on thatmedium.

In accordance with the present invention, the meta information relatedto each content within plural terminals connected to the contentretrieving device by the network is managed within the contentretrieving device (e.g., in a tree shape). Partial meta information(e.g., meta information corresponding to a partial tree) among this metainformation is distributed and managed within the terminal. Thus, evenwhen content are frequently added, moved, deleted, or copied, etc.within the terminal connected to the content retrieving device by thenetwork, or between the terminals, it is possible to reduce the numberof access times to the meta information held by the content retrievingdevice in order to manage the content within each terminal, and also toreduce the amount of meta information as a backup object and therebyalso reduce the processing load on a server.

The above and/or other aspects, features and/or advantages of variousembodiments will be further appreciated in view of the followingdescription in conjunction with the accompanying figures. Variousembodiments can include and/or exclude different aspects, featuresand/or advantages where applicable. In addition, various embodiments cancombine one or more aspects or features of other embodiments whereapplicable. The descriptions of aspects, features and/or advantages ofparticular embodiments should not be construed as limiting otherembodiments or the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings, wherein:

FIG. 1 is a view showing a structure of a content managing systemaccording to a first embodiment of the present invention;

FIG. 2 is a flow chart showing a processing procedure of a contentretrieving device according to the first embodiment of the presentinvention;

FIG. 3 is a view showing an example of terminals connected to a server;

FIG. 4 is a view showing a first example of local content within the PCterminal;

FIG. 5 is a view showing a first example of local content within thevideo camera terminal;

FIG. 6 is a view showing a first example of local content within thedigital camera terminal;

FIG. 7 is a view showing a first example of partial meta informationmanaged within the PC terminal;

FIG. 8 is a view showing a first example of meta information managedwithin a server;

FIG. 9 is a view showing a second example of meta information managedwithin the server;

FIG. 10 is a view showing an example of the display of a GUI screen forinputting a retrieving condition and outputting a retrieving result;

FIG. 11 is a view showing an example of a query for obtaining managingterminal information;

FIG. 12 is a view showing an example of obtaining a result of themanaging terminal information;

FIG. 13 is a view showing a first example of a query for obtainingpartial meta information managed within the PC terminal;

FIG. 14 is a view showing an example of a query for obtaining metainformation managed within the server with the server as a managingterminal;

FIG. 15 is a view showing a first example of a retrieving result withrespect to the partial meta information of the managing terminal;

FIG. 16 is a view showing an example of an content obtaining result;

FIG. 17 is a view showing an example of a result in which the contentobtaining results are integrated;

FIG. 18 is a view showing a structure of a content managing system inaccordance with a second embodiment of the present invention;

FIG. 19 is a flow chart showing a processing procedure of a contentretrieving device in accordance with the second embodiment of thepresent invention;

FIG. 20 is a view showing a second example of local content within thePC terminal;

FIG. 21 is a view showing a second example of a query for obtainingpartial meta information managed within the PC terminal;

FIG. 22 is a view showing a second example of a retrieving result withrespect to the partial meta information of a managing terminal;

FIG. 23 is a view showing another example of a query for obtainingpartial meta information managed within the PC terminal; and

FIG. 24 is a view showing another example of a retrieving result withrespect to the partial meta information of the managing terminal.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will next be explained withreference to the drawings.

Meta information used in the present specification includes plural kindsof information relating to content details, such as ID for identifyingthe content, and the identification information of a terminal storingthe content.

FIG. 1 shows an example of a content managing system in accordance withone embodiment of the present invention.

The content managing system of this embodiment includes a server (i.e.,content managing device) 6 and plural terminals 50 and 51 able tocommunicate with the server 6 through a network 20.

The plural terminals include a first terminal 50 and a second terminal51. The first terminal 50 has a partial meta information managingfunction for managing the meta information relating to the content heldwithin another terminal (e.g., the second terminal) and itself. Thesecond terminal 51 does not have a partial meta information managingfunction.

The content managing system of this example includes at least one firstterminal 50 and one second terminal 51. However, alternative embodimentsare possible in which no second terminal 51 exists.

The network 20 between the server 6 and each terminal may be a LAN suchas a home network, for example.

The network 21 between the first terminal 50 and the second terminal 51as a managing object of this first terminal 50 may be the same networkas the network 20, and may be also a network different from the network20.

The terminals 50 and 51 may include a PC terminal, an informationterminal, a portable terminal, or other electrical appliances, forexample.

As shown in FIG. 1, the server 6 of this embodiment has a displayrequest section 310, a content retrieving section 330, a metainformation retrieving section 350, a meta information managing section340, a content display section 360, a communication section 390 and ameta information database (meta information DB) 720.

The meta information DB 720 stores meta information relating to content(i.e., multimedia content data) stored to a local content group 510within each first terminal 50 and a local content group 610 within eachsecond terminal 51.

The display request section 310 includes an interface for inputting aretrieving display request 90 from a user, and the inputted retrievingdisplay request signal is transmitted to the content retrieving section330.

The content retrieving section 330 performs processing for extracting ameta information retrieving condition from the retrieving displayrequest signal transmitted from the display request section 310, andtransmitting the meta information retrieving condition to the metainformation retrieving section 350.

Further, the content retrieving section 330 performs processing forreceiving the meta information transmitted from the meta informationretrieving section 350 as a retrieving result.

Further, the content retrieving section 330 performs processing fortransmitting a content retrieving request signal for executing contentretrieval to the first terminal 50 and the second terminal 51 via thecommunication section 390 and the network 20 based on the received metainformation, and giving instructions of the retrieval of the content.

Further, the content retrieving section 330 performs processing forintegrating the content retrieving result transmitted from the firstterminal 50 and the second terminal 51 and acquiring the contentretrieving result as content retrieving result 730.

The meta information managing section 340 adds, updates and deletes themeta information with respect to the meta information DB 720.

Further, the meta information managing section 340 performs processingfor managing update information of the meta information.

Further, the meta information managing section 340 performs processingfor receiving the meta information according to the condition of theretrieval executed by the meta information retrieving section 350 fromthe meta information DB 720 through the meta information retrievingsection 350.

Further, the meta information managing section 340 performs processingto judge whether or not reference link information to the first terminal50 is included within the received meta information.

Further, the meta information managing section 340 performs processingfor transmitting the information of a terminal as a retrieving object ofthe content and meta information (hereinafter also called partial metainformation) managed by this terminal to the meta information retrievingsection 350 based on the result of the above judgment. Namely, when itis judged that the reference link information is included, the metainformation managing section 340 performs processing for givinginstructions to the meta information retrieving section 350 so as toexecute further retrieval with respect to a partial meta information DB520 within the terminal 50 corresponding to a link destination shown bythis reference link information.

The meta information retrieving section 350 calculates the metainformation according to the condition from the meta information DB 720based on the meta information retrieving condition transmitted from thecontent retrieving section 330, and transmits this meta information tothe meta information managing section 340.

Further, the meta information retrieving section 350 transmits a partialmeta information retrieving request signal and retrieval instructionsrequiring the retrieval of the partial meta information to the firstterminal 50 as a retrieving object via the communication section 390 andthe network 20 when instructions for executing further retrieval aregiven from the meta information managing section 340.

Further, the meta information retrieving section 350 calculates the metainformation as a retrieving result from the meta information transmittedfrom the meta information DB 720 or the partial meta information DB 520within the first terminal 50, and transmits this calculated metainformation to the content retrieving section 330.

The content display section 360 receives the content retrieving result730 from the content retrieving section 330, and displays thisretrieving result in a display.

The content display section may also display attributes, etc. of thecontent instead of the content itself in accordance with a contentclassification. For example, in the case of video content, a list ofvideo scenes may also be displayed as thumbnails. In the case of musicand photographs, a title list of the music and the photographs may alsobe displayed.

The communication section 390 transmits the content retrieving requestsignal or the meta information retrieving request signal received fromthe content retrieving section 330 or the meta information retrievingsection 350, respectively, to a communication section 190 within thefirst terminal 50 or a communication section 290 within the secondterminal 51 via the network 20.

Further, the communication section 390 receives the content retrievingresult or the meta information retrieving result transmitted from thecommunication section 190 within the first terminal 50 or thecommunication section 290 within the second terminal 51 via the network20, and respectively transmits the content retrieving result or the metainformation retrieving result to the content retrieving section 330 orthe meta information retrieving section 350, respectively.

In addition, the server 6 may include a function for managing the metainformation of the second terminal 51.

Further, the server 6 may include a local content group and a contentmanaging section. In this case, the server 6 itself also performsterminal functions.

Next, as shown in FIG. 1, the first terminal 50 of this embodiment has acontent managing section 120, a content retrieving section 130, apartial meta information managing section 140, a partial metainformation retrieving section 150, the communication section 190, thelocal content group 510 and the partial meta information database (i.e.,partial meta information DB) 520.

For example, the local content group 510 stores various contentrepresented by document data, a computer program, a broadcasting programor images captured from a video, a picture photographed by a digitalcamera, a music album, and a musical piece, etc.

The partial meta information DB 520 stores meta information relating tothe content stored to the local content group 510, and meta informationrelating to the content stored to a local content group 610 of thesecond terminal 51 as a managing object.

The content managing section 120 adds, updates and deletes content withrespect to the local content group 510. In this case, the contentmanaging section 120 transmits a partial meta information update requestsignal for requiring the update of the partial meta information to thepartial meta information managing section 140, and gives instructionsfor updating the partial meta information DB 520 and the partial metainformation update information.

The content managing section 120 preferably transmits a partial metainformation update request signal to the partial meta informationmanaging section 140 as rapidly as possible when the local content group510 is updated.

When the content retrieving section 130 receives the content retrievingrequest signal from the server 6 through the communication section 190,the content retrieving section 130 executes retrieval processing of thelocal content group 510.

Further, the content retrieving section 130 transmits the above metainformation retrieving request signal to the partial meta informationretrieving section 150 with respect to the meta information retrievingrequest signal from the server 6 transmitted from the communicationsection 190, and gives instructions of the retrieving execution to thepartial meta information DB 520.

The partial meta information managing section 140 adds, updates anddeletes the partial meta information with respect to the partial metainformation DB 520.

Further, the partial meta information managing section 140 performsprocessing for updating the update information of the partial metainformation.

Further, the partial meta information managing section 140 performsprocessing for updating the partial meta information DB 520 based on thepartial meta information update request signal from the content managingsection 120 and the content managing section 220 of the second terminal51 as a managing object.

The partial meta information managing section 140 transmits the metainformation update request signal for requiring the update of the metainformation to the server 6 in predetermined timing, and the server 6receiving this meta information update request signal may update thepertinent meta information.

For example, the predetermined timing may be set to various timings suchas periodic timing (e.g., once a day), a power turning-on time of theterminal, a connecting time of the terminal to the network 20, andcombinations thereof, etc.

The partial meta information retrieving section 150 receives the metainformation retrieving request signal from the content retrievingsection 130, and executes the retrieval of the meta informationaccording to the retrieving condition with respect to the partial metainformation DB 520, and transmits the meta information obtained as thisresult to the content retrieving section 130.

The communication section 190 transmits the content retrieving result orthe meta information retrieving result received from the contentretrieving section 130 and the partial meta information retrievingsection 150 to the communication section 390 within the server 6 via thenetwork 20.

Further, the communication section 190 receives the content retrievingrequest signal or the meta information retrieving request signaltransmitted from the communication section 390 within the server 6 viathe network 20, and respectively transmits the content retrievingrequest signal or the meta information retrieving request signal to thecontent retrieving section 130 or the meta information retrievingsection 150 together with the retrieving instructions.

Various embodiments are possible for the the first terminal 50.

For example, the first terminal 50 may not include a local content group510 and includes a function for managing only the meta informationrelating to the second terminal 51. Conversely, the first terminal 50may include a function for managing only the meta information relatingto itself.

Further, for example, the first terminal 50 may include a function formanaging the meta information relating to another terminal in additionto the function for managing the meta information relating to itself.

Next, as shown in FIG. 1, the second terminal 51 has a content managingsection 220, a content retrieving section 230, a communication section290 and a local content group 610. This second terminal 51 differs fromthe first terminal 50 in that the second terminal 51 itself has nofunction for managing the partial meta information.

The local content group 610 is similar to the local content group 510 ofthe terminal 50. For example, the local content group 610 stores variouscontent represented by document data, a computer program, a broadcastingprogram or an image captured from a video, a picture photographed by adigital camera, a music album and a musical piece, etc.

The content managing section 220 adds, updates and deletes content withrespect to the local content group 610. Further, at this time, thecontent managing section 220 transmits the above partial metainformation update request signal to the partial meta informationmanaging section 140 of the first terminal 50 with the itself as amanaging object, updates the partial meta information DB 520, and givesinstructions of the update of the partial meta information.

When the local content group 610 is updated, the content managingsection 220 preferably transmits the partial meta information updaterequest signal to the partial meta information managing section 140 ofthe first terminal 50 with the self terminal as a managing object asrapidly as possible.

When the content retrieving section 230 receives the content retrievingrequest signal from the server 6 through the communication section 290,the content retrieving section 230 executes the retrieval processing ofthe local content group 610.

The communication section 290 transmits the local content retrievingresult received from the content retrieving section 230 to thecommunication section 390 within the server 6 via the network 20.

Further, the communication section 290 receives the content retrievingrequest signal transmitted from the communication section 390 within theserver 6 via the network 20, and transmits the content retrievingrequest signal to the content retrieving section 230.

Procedures for adding, updating and deleting the meta information (e.g.,partial meta information) in the meta information managing section 340and the partial meta information managing section 140 may be performedby using a publicly known technique. Japanese Patent Application (KoKai)No. 2002-297601 discloses an example of this publicly known technique.

An example of the processing operation of the content retrieving devicewill next be explained.

FIG. 2 shows one example of a flow chart showing the processingoperation of this content retrieving device.

In this example, as shown in FIG. 3, three terminals including PC 101 asthe first terminal 50 having the partial meta information managingfunction, video camera 102 as the second terminal 51 having no partialmeta information managing function, and digital camera 103 eachconnected to the server 6 by the network 20.

Further, this example illustrates a user operating the interface of theserver 6 and retrieving and displaying a list of screen image content inthe PC terminal 101, the video camera 102 and the digital camera 103.

FIGS. 4 to 6 respectively show examples of content stored to the localcontent group within each of the three terminals including the PC 101,the video camera 102 and the digital camera 103.

As shown in FIG. 4, the PC 101 holds two items, “news program A” and“gourmet program B,” which are classified as video content within thelocal content group 510.

Further, as shown in FIG. 5, the video camera 102 holds one contentitem, “home video X,” which is classified as video content within thelocal content group 610.

Further, as shown in FIG. 6, the digital camera 103 holds one contentitem, “travel C,” which is classified as video content within the localcontent group 610.

In this example, the meta information relating to the local contentgroup within the PC 101 and the meta information relating to the localcontent group within the video camera 102 are managed as partial metainformation within the PC 101.

Further, the meta information relating to the local content group withinthe digital camera 103 is managed within the server 6.

Further, the server 6 is uniquely responsible for management of the metainformation group relating to the local content group within each ofthese three terminals.

FIG. 7 shows one example of the partial meta information managed withinthe PC 101 as a first terminal.

In this example, the meta information for each described terminal isarranged within a range surrounded by a meta information tag. Withrespect to the meta information relating to one terminal, the metainformation for each described content is arranged within a rangesurrounded by a terminal tag that includes a terminal name as anattribute.

Further, with respect to the meta information of each content,information relating to the content is structurally arranged within arange surrounded by a tag showing the content classification includingthe terminal name, a data type and content ID as attributes.

FIG. 8 shows a first example of the meta information managed within theserver 6, and FIG. 9 similarly shows a second example of this metainformation.

FIG. 8 shows an example in which no copy of the partial meta information(the meta information of the PC 101 and the meta information of thevideo camera in this example) managed in the first terminal 50 (PC 101in this example) having a partial meta information managing function isheld within the server 6. FIG. 9 shows an example in which the abovecopy is held within the server 6.

Namely, when FIGS. 8 and 9 are compared with each other, information foreach described local managing content group is arranged within a rangesurrounded by the meta information tag in each case.

However, with respect to the PC 101 as a terminal (hereinafter alsocalled a managing terminal) for managing the partial meta information,only reference link information is described within the tag in FIG. 8,and no copy of the meta information is described. In contrast to this,in FIG. 9, the copy of the meta information is described in addition tothe reference link information.

Further, in the example of each of FIGS. 8 and 9, the meta informationis described with respect to the digital camera 103.

FIG. 8 shows that no managing terminal is described within the localmanaging content group tag, and information not described with respectto the managing terminal within the local managing content group tag isthe meta information directly managed by the server 6. In contrast tothis, FIG. 9 shows that MANAGING_TERMINAL=“SERVER” is clearly describedwithin the local managing content group tag. FIGS. 8 and 9 differ fromeach other in this point.

In this example, the meta information is described in an XML format, butis not limited to this format.

In the following, a case using the meta information holding the copy ofthe partial meta information managed within the managing terminal asshown in FIG. 9 is explained as an example.

In FIG. 9, the local content group held by the server 6 includes threecontent items including video content “new program A” of the PC 101,video content “home video X” of the video camera 102, and image content“travel C” of the digital camera 103. However, newest content of the PC101 and the video camera 102 are managed by the PC 101, and a linkdestination to the PC 101 corresponding to this partial meta informationshows “/META_INFORMATION” within the meta information DB correspondingto the local content group in the PC 101.

Further, the example shows that newest content in the digital camera 103are managed by the server 6.

Further, the example also shows an attribute “UPDATE_FLAG” indicatingwhether or not information unreflected in the server 6 with respect tochanging content of the meta information is included within the metainformation managed by the PC 101 as a first terminal.

In this example, when the attribute value of the update flag is “True”,the unreflected meta information is included. In contrast to this, whenthe attribute value is “False”, no unreflected meta information isincluded.

For example, the attribute value of the update flag is set as follows.

When the partial meta information managing section 140 of the firstterminal 50 executes the update of the partial meta information DB 520,the partial meta information managing section 140 transmits to theserver 6 a notification message showing that the partial metainformation DB 520 is updated.

The server 6 receiving this notification message changes the attributevalue of the update flag of the pertinent meta information to “True”.

In this case, when the partial meta information managing section 140 ofthe first terminal 50 executes the update of the partial metainformation DB 520 and timing for transmitting a meta information updaterequest signal to the server 6 is attained within a predetermined time,the partial meta information managing section 140 may also transmit themeta information update request signal after the attainment of thistiming instead of the transmission of the above notification message.

When the server 6 receives the meta information update request signalfrom the first terminal 50, the server 6 updates the pertinent metainformation and changes the attribute value of the update flag to“False”.

In an alternative possible embodiment, the meta information is alwaystreated as (possibly) un-updated information without arranging theupdate flag (the attribute value of the update flag is always treated as“True”).

Further, as shown in FIG. 8, when the meta information including no copyof the partial meta information managed within the first terminal 50 isadopted, no update flag is arranged and the meta information is alwaystreated as (possibly) un-updated information.

In this example, it is assumed that “gourmet program B” is recorded tothe PC 101 as a new program, and the meta information corresponding tothis video content is reflected in the partial meta information DB 520within the PC 101 as shown in FIG. 7, but is not yet reflected in themeta information DB 720 within the server 6.

In the examples of FIGS. 8 and 9, for brevity of the explanation, onlyone PC 101 and server 6 are shown in the terminal for managing the localcontent group. However, when plural managing terminals exist, inaddition to server 6, information for each described managing terminal(i.e., every local managing content group) is arranged within the metainformation tag in FIG. 9.

An example of a processing operation of a content retrieving deviceaccording to the present invention will next be explained with referenceto FIG. 2.

First, the server 6, connected to each of the terminals 50, 51 throughthe network 20, waits in a wait state for a retrieving display requestfrom a user (step S11).

FIG. 10 shows one example of a GUI screen for setting a conditionrelating to the retrieving display request by the user.

This example shows performing the retrieving display request ofobtaining and displaying a content item classified as video content fromthe local content group within each terminal will be explained.

For example, the user selects “video” in content classification and “nocondition” with respect to the item name and the item value from a dropdown menu in the GUI shown in FIG. 10, and inputs a setting condition bypushing-down a retrieving button, for example the button labeled“retrieval.”

The server 6 checks the existence of the input of the retrieving displayrequest performed by the user in the state of step S11 (step S12). Ifthere is no retrieving display request, operation is returned to thestep S11. In contrast to this, if there is a retrieving display request,operation proceeds to a step S13.

In the step S13, the server 6 retrieves and acquires content conformedto the meta information retrieving condition calculated from theretrieving display request obtained in the step S12 among the metainformation corresponding to each terminal under sole management of theserver.

First, a query (i.e., retrieving condition) for the meta informationretrieval corresponding to the setting condition is generated based onthe setting condition set as mentioned above.

Here, the query for the meta information retrieval is issued to both themanaging terminal for managing the local content group and the server 6.

Therefore, a query for obtaining information of the managing terminalholding the managing information is issued to the meta information DB720 within the server 6 in order to know which managing terminal holdsthe newest managing information relating to the local content group ofeach terminal at the present time.

FIG. 11 shows one possible example of the query for obtaining themanaging terminal information. FIG. 12 shows one possible example ofresults obtained by applying this query.

In the following explanation, W3C standard query description languageXQuery (see URL: http://www.w3.org/TR/xquery for more information) isused, but the present invention is not limited to this XQuery.

The meaning of the query shown in FIG. 11 is as follows.

(First line: retrieving range) Content showing that the update flag is“True” (i.e., the newest managing information lies on the managingterminal side instead of the server 6) for each local managing contentgroup substituted one by one as a value of $local_mng_grp by using a FORparagraph, and the following steps of the respective lines are appliedwith respect to each $local_mng_grp.

(Second line: value substitution) The value of an attribute tag“MANAGING_TERMINAL” of the $local_mng_grp is obtained as a text value byusing a LET paragraph, and these values are substituted into and storedin a list $mng_device one by one.

(Third line: value substitution) The value of an attribute tag“LINK_DESTINATION” of the $local_mng_grp is obtained as a text value byusing the LET paragraph, and these values are substituted into andstored in a list $link one by one.

(Fourth and subsequent lines: result transmission) The values of lists$local_mng_grp and $link calculated in the steps of the second and thirdrows are respectively surrounded by element tags “MANAGING_TERMINAL” and“LINK_DESTINATION” one by one, and these values are transmitted asretrieving results surrounded by an element tag“LOCAL_MANAGING_TERMINAL_INFORMATION”.

In this example, the number of “LOCAL_MANAGING_CONTENTS_GROUP” elementtags corresponding to the query retrieving condition of FIG. 11 is one,and this element tag is transmitted as one“LOCAL_MANAGING_TERMINAL_INFORMATION” element tag, as shown in FIG. 12.

Such a retrieving result of the managing terminal information indicatesthat one portion of the meta information held within the server 6 ismanaged by the PC 101 as a managing terminal.

The server 6 judges whether or not a managing terminal holding thenewest managing information relating to the local content group of eachterminal at the present time exists based on the managing terminalinformation acquired in this way (step S14).

In step S14 of this example, the server 6 retrieves and obtains thepartial meta information held in the managing terminal if the managingterminal exists, and only the meta information within the server 6 maybe set to a retrieving object if no managing terminal exists.

Accordingly, when there is a managing terminal as the retrieving result(in the case of Yes in the step S14), the server 6 specifies themanaging terminal in which a link to the partial meta informationexists, and executes the retrieval with respect to the partial metainformation managed by this specified managing terminal (step S15).

Further, the server 6 executes the retrieval with respect to the metainformation (except for the meta information in which the attributevalue is “True”) managed by the server 6, and integrates theseretrieving results of the partial meta information (step S16).

The server 6 uses this integrated result in subsequent processing.

At this time point, all the partial meta information relating to themanaging terminal may also be obtained and flashed (written back) withrespect to the meta information DB 720. In this case, the update flag inthe pertinent meta information is updated to “False”.

In contrast to this, when no managing terminal exists as the retrievingresult (in the case of No in the step S14), the server 6 executes theretrieval with respect to the meta information (except for the metainformation in which the attribute value is “True”) managed by theserver 6 (step S17).

The server 6 uses this retrieving result in subsequent processing.

In step S13, the server 6 applies a retrieving query for obtaining theID of the managing terminal managing the partial meta information asshown in FIG. 11 to the meta information DB 720.

The query shown in FIG. 11 obtains all the values of “MANAGING_TERMINAL”and “LINK_DESTINATION” attributes with respect to the content showingthat the attribute value of the update flag is “True” among a path“/META_INFORMATION/LOCAL_MANAGING_CONTENTS_GROUP”

The retrieving result of the terminal ID (plural terminal IDs may alsobe set) of the managing terminal managing the partial meta informationcorresponding to this query is provided as shown in FIG. 12, and it isknown that the managing terminal is “PC” and the link destination is“/META_INFORMATION”.

This result indicates that the judgment in step S14 is yes, and theserver 6 performs the processing of steps S15 and S16.

In the step S15, the server 6 executes the retrieval of the partial metainformation using the query shown in FIG. 13 with respect to the partialmeta information DB 520 within the managing terminal managing thepartial meta information calculated as mentioned above, i.e., the PC101.

Further, the server 6 issues the query shown in FIG. 14 to the metainformation DB 720 within the server 6 in the step S15.

The server 6 acquires a retrieving result (including the metainformation relating to three content items) with respect to the partialmeta information of the managing terminal shown in FIG. 15, and aretrieving result (the retrieving result becomes an empty set sincethere is no pertinent meta information) with respect to the metainformation within the server 6, and integrates these retrieving results(step S16).

The results of this integration are similar to those in FIG. 15.

If the meta information shown in FIG. 15 is obtained, the contentretrieving section 330 within the server 6 specifies the ID (ID=1, ID=2and ID=4 in the case of this example) of content to which the contentretrieval should be applied, and a terminal (terminal=“PC” with respectto ID=1 and ID=4, and terminal=“video camera” with respect to ID=2 inthe case of this concrete example) including this ID on the basis ofthis meta information, and executes obtaining of the respective contentwith respect to the respective terminals (step S18).

A publicly known technique may be used in the retrieving display oflocal content based on the meta information.

The content items are here obtained in accordance with, for example, aUPnP protocol by utilizing the URL corresponding to a file storing placeof each content.

The obtaining results of content items with ID=2 and ID=4 in the PC 101are provided as shown in FIG. 4, and the obtaining results of contentwith ID=2 in the video camera 102 are provided as shown in FIG. 16.

The server 6 integrates the content retrieving results transmitted fromthese respective terminals, and makes content retrieving result 730(step S19).

FIG. 17 shows the details of content corresponding to the result inwhich these content retrieving results are integrated. In this example,as shown in FIG. 17, these content include “news program A”, “gourmetprogram B” and “home video X”.

The server 6 finally displays the above content retrieving result 730 inthe display as the content display section 360 (step S20).

As mentioned above, the method of the content display may be applied inaccordance with the classification of the content.

For example, in the case of the video content, a thumbnail, i.e., a listof video scenes may be displayed instead of the video contentthemselves. In the case of music and photographs, a title list may bedisplayed.

As explained above, in accordance with this embodiment, the number ofaccess times to the server can be reduced in the addition, the movementand the copy of the meta information in the management of the metainformation relating to the content. Thus, the load of server processingcan be reduced.

Other embodiments will next be explained emphasizing different points.

FIG. 18 shows an example of a content managing system relating to asecond embodiment of the present invention.

As can be seen from the comparison of FIGS. 18 and 1, this embodimentdiffers from the previous embodiment in that the server 6 furtherincludes a retrieving query reissuing section 380.

A content retrieving section 330 of the server 6 of this embodiment hasthe following functions in addition to the function of the contentretrieving section 330 of the previous embodiment. Namely, when thecontent retrieving section 330 executes content retrieval with respectto the terminals 50, 51 and fails in the content retrieval because thepower source of a certain terminal is turned off, etc., the contentretrieving section 330 has a function for judging whether or not a copyor a digest of content of the certain terminal exists in a terminaldifferent from the certain terminal, and requesting the reissue of aretrieving query with respect to the different terminal from theretrieving query reissuing section 380 when the copy or the digestexists. The content retrieving section 330 also has a function forreceiving a query for re-retrieval transmitted from the retrieving queryreissuing section 380, and again executing the retrieval with respect tothe different terminal.

The retrieving query reissuing section 380 of the server 6 of thisembodiment generates a retrieving query with respect to the copy or thedigest of predetermined desirable content based on the request of thereissue of the retrieving query received from the content retrievingsection 330, and transmits the generated retrieving query to the contentretrieving section 330.

The processing operation of the content retrieving device will next beexplained by using an example.

FIG. 19 shows one example of a flow chart showing the processingoperation of this content retrieving device.

The processing flow of a content managing device of this embodimentdiffers from the processing flow in the first content managing device inthat, when the content managing device fails in the content retrievalfor reasons of turning-off of the power source of a terminal, etc. afterthe execution of the step S18 in the processing flow in the contentmanaging device shown in FIG. 19, the content managing device executes astep S181 for again issuing the retrieving query with respect to anotherterminal having the copy or the digest of these content.

Here, as an example according to this embodiment, the local contentgroups within the PC 101 and the video camera 102 are respectively setas shown in FIGS. 20 and 5.

Namely, it is assumed that video content HVX.mpg, entitled “home videoX,” in the video camera 102 are copied to the PC 101, and only the titleis rewritten to “home video Y”.

The ID of the original content and the ID of content obtained by copyingthe original content are set to the same value. When the content arecopied, it is possible to easily construct a system for taking over thesame content ID.

Further, it is assumed that the example used in this embodiment has thesame content holding condition as the example used in the previousembodiment except that the above content are copied.

In this case, it is also assumed that all changes in the metainformation in the managing terminal are reflected in the metainformation DB 720 within the server 6.

A list of content entitled “home video X” among the video content ineach terminal is retrieved and displayed by operating the interface ofthe server 6 by a user, for example. Further, in the following example,the power source of the video camera 102 is turned off at the retrievingtime.

Steps S1 to S4 are similar to those in the previous embodiment.

When the server 6 judges that a managing terminal exists in the stepS14, the server 6 issues a query to acquire meta information as shown inFIG. 21 in a step S15.

In a step S16, the server 6 then obtains the meta information shown inFIG. 22 as a retrieving result of the meta information.

As shown in FIG. 22, the existence of video content entitled “home videoX” within the video camera 102 is confirmed.

However, in this example, since the power source of the video camera 102is turned off as mentioned above, the retrieving acquirement of thevideo content in the step S18 is unsuccessful.

The server 6 refers to the ID of the content from the meta informationobtained in FIG. 22, and obtains content ID=2.

The server 6 issues a query for retrieving the meta information relatingto content having a tag value=“2” of “ID” as shown in FIG. 23 to boththe managing terminal for managing the local content group and theserver 6 (step S181), and obtains the meta information as shown in FIG.24 as a retrieving result.

Thus, it is confirmed that the content having the title=“home video Y,”as a copy of the desired content, exists within the PC 101, and it isknown that content can be retrieved and obtained.

Next, if the server 6 obtains the meta information shown in FIG. 24, theserver 6 specifies the ID (ID=2 in the case of this example) of contentto which the content retrieval should be applied, and a terminal(terminal=“PC” in the case of this example) including this ID based onthis meta information, and executes obtaining of the respective contentwith respect to the respective terminals (step S181).

The server 6 then integrates the content retrieving results transmittedfrom the terminals, and makes content retrieving result 730 (step S19).In this example, the content having the title=“home video Y” is made.

The server 6 displays the obtained content retrieving result 730 in thedisplay as the content display section 360 (step S20).

The above example describes a method for specifying the existence of thecopy of content unsuccessfully retrieved. However, the existence of aprocessed object such as a digest of the content, etc. is similarlyspecified. For example, this specifying can be realized by a similarmethod by separately defining the original content ID at a recordingtime point in addition to the content ID finally issued.

In the above description, the case that the power source of a terminalis turned off is used as a case in which the content obtaining withinthe terminal is unsuccessful. However, no unsuccessful cause is limitedto this case. For example, various cases such as a case in whichcommunication is unsuccessful when a home server and each terminal areconnected by a network in wireless communication and are separated by 10meters or more in distance from each other as in a Bluetooth, etc. areconsidered.

As explained above, in accordance with this embodiment, even whencontent are frequently copied and moved between terminals connected tothe server by the network, it is possible to reduce the number of accesstimes to the meta information held in the server to manage the contentwithin each terminal, and the meta information amount as a backup objectso that the processing load of the server can be reduced.

Further, even when one portion of the terminal fails in the retrievalobtaining of content by turning-off the power source, etc., a user canretrieve, obtain and regenerate predetermined desirable content asrapidly as possible by retrieving and obtaining a copy and a digest ofthis content from another terminal.

Each of the above functions can be also realized by describing thisfunction as software and processing this function by a computer having asuitable mechanism.

Further, this embodiment can be also executed as a program for making acomputer execute a predetermined means, a program for making thecomputer function as a predetermined means, or a program for making thecomputer realize a predetermined function. In addition, this embodimentcan be also executed as a recording medium readable by the computer andrecording this program.

1. A content retrieving device for retrieving content stored in aterminal through a network, said content retrieving device comprising:means for storing a second terminal ID of a managing terminal thatstores a meta information, said meta information including pluralinformation relating to said content including a content ID thatidentifies said content and a first terminal ID of a terminal thatstores the content; means for inputting a retrieving condition thatspecifies at least one information in the plural information relating tosaid content; means for obtaining the meta information that includes theat least one information in said retrieving condition from the managingterminal having the second terminal ID stored in said means for storing;means for specifying said content ID based on the meta informationobtained by the means for obtaining, and for specifying the firstterminal ID of the terminal storing the content; and means fortransmitting a request for obtaining the content relating to saidcontent ID specified by said means for specifying through said networkto the terminal having the first terminal ID specified by the means forspecifying.
 2. The content retrieving device according to claim 1,wherein said means for storing stores said second terminal ID, a copy ofsaid meta information, and a state control information that is set toone of a first state and a second state, the first state indicating thecopy of the meta information is equal to a newest meta informationstored on the managing terminal having the second terminal ID and thesecond state indicating no copy of the meta information is equal to thenewest meta information stored on the managing terminal having thesecond terminal ID, and said means for obtaining obtains said metainformation from said means for storing instead of from the managingterminal having the second terminal ID when said control information isset to the first state.
 3. The content retrieving device according toclaim 2, wherein the content retrieving device further comprises: meansfor receiving notification information showing said second state fromsaid managing terminal through said network; and means for setting thecontrol information relating to said managing terminal among the controlinformation stored to said means for storing to said second state whensaid notification information is received by the means for receiving. 4.The content retrieving device according to claim 3, wherein the contentretrieving device further comprises: means for obtaining the newest metainformation from said managing terminal through said network; and meansfor updating the meta information relating to said managing terminalamong the meta information stored on said means for storing to theobtained newest meta information and for changing said correspondingcontrol information to said first state when the newest meta informationis obtained by the means for obtaining.
 5. The content retrieving deviceaccording to claim 1, wherein said means for storing also stores themeta information that includes the plural information relating to thecontent stored into the terminal to be directly managed, and also storesthe first identification information of the terminal storing thesecontent with respect to the terminal to be directly managed, and saidmeans for obtaining also obtains the meta information that includes theat least one information in said retrieving condition among the metainformation stored in said means for storing with respect to theterminal to be directly managed.
 6. The content retrieving deviceaccording to claim 1, wherein the plural information in said metainformation includes at least information showing a classification ofthe content relating to the meta information, information showing atitle of the content, and information showing a file name of thecontent.
 7. The content retrieving device according to claim 1, whereinthe content retrieving device further comprises: means for receivingcontent relating to said request from the terminal transmitting saidrequest; and means for presenting information relating to the contentreceived by the means for receiving.
 8. The content retrieving deviceaccording to claim 1, wherein the meta information includes the firstidentification information of the terminal storing a copy or a digest ofan identified content when the content relating to said meta informationis the copy or the digest of the identified content, said means forobtaining obtains the meta information relating to said copy or digestwhen said identified content cannot be received by said means forreceiving although the request for obtaining said identified content istransmitted to the terminal storing said identified content by saidmeans for transmission through said network, said means for specifyingspecifies the first terminal ID of the terminal storing said copy ordigest based on the meta information obtained by said means forobtaining, and said means for transmission transmits the request forobtaining said copy or digest to the terminal having the first terminalID through said network. 9-24. (canceled)
 25. A computer readable mediumstoring a content retrieving program which causes a computer to perform:storing a second terminal ID of a managing terminal that stores a metainformation, said meta information including plural information relatingto said content including a content ID that identifies said content anda first terminal ID of a terminal that stores the content; inputting aretrieving condition that specifies at least one information in theplural information relating to said content; obtaining the metainformation that includes the at least one information in saidretrieving condition from the managing terminal having the secondterminal ID stored in storing; specifying said content ID based on themeta information obtained by the obtaining, and specifying the firstterminal ID of the terminal storing the content; and transmitting arequest for obtaining the content relating to said content ID specifiedby said specifying through said network to the terminal having the firstterminal ID specified by the specifying.
 26. The computer readablemedium according to claim 25, wherein said storing stores said secondterminal ID, a copy of said meta information, and a state controlinformation that is set to one of a first state and a second state, thefirst state indicating the copy of the meta information is equal to anewest meta information stored on the managing terminal having thesecond terminal ID and the second state indicating no copy of the metainformation is equal to the newest meta information stored on themanaging terminal having the second terminal ID, and said obtainingobtains said meta information from said storing instead of from themanaging terminal having the second terminal ID when said controlinformation is set to the first state.
 27. The computer readable mediumaccording to claim 26, wherein said program further comprises: receivingnotification information showing said second state from said managingterminal through said network; and setting the control informationrelating to said managing terminal among the control information storedto said storing to said second state when said notification informationis received by the receiving.
 28. The computer readable medium accordingto claim 27, wherein said program further comprises: obtaining thenewest meta information from said managing terminal through saidnetwork; and updating the meta information relating to said managingterminal among the meta information stored in said storing to theobtained newest meta information and changing said corresponding controlinformation to said first state when the newest meta information isobtained by the obtaining.
 29. The computer readable medium according toclaim 25, wherein said storing also stores the meta information thatincludes the plural information relating to the content stored into theterminal to be directly managed, and also stores the firstidentification information of the terminal storing these content withrespect to the terminal to be directly managed, and said obtaining alsoobtains the meta information that includes the at least one informationin said retrieving condition among the meta information stored by saidstoring with respect to the terminal to be directly managed.
 30. Thecomputer readable medium according to claim 25, wherein the pluralinformation in said meta information includes at least informationshowing a classification of the content relating to the metainformation, information showing a title of the content, and informationshowing a file name of the content.
 31. The computer readable mediumaccording to claim 25, wherein said program further comprises: receivingcontent relating to said request from the terminal transmitting saidrequest; and presenting information relating to the content received bythe receiving.
 32. The computer readable medium according to claim 25,wherein the meta information includes the first identificationinformation of the terminal storing a copy or a digest of an identifiedcontent when the content relating to said meta information is the copyor the digest of the identified content, said obtaining obtains the metainformation relating to said copy or digest when said identified contentcannot be received by said receiving although the request for obtainingsaid identified content is transmitted to the terminal storing saididentified content by said transmitting through said network, saidspecifying specifies the first terminal ID of the terminal storing saidcopy or digest based on the meta information obtained by said obtaining,and said transmitting transmits the request for obtaining said copy ordigest to the terminal having the first terminal ID through saidnetwork.
 33. A content retrieving device for retrieving content storedin a terminal through a network, said content retrieving devicecomprising: an inputting device configured to input a retrievingcondition that specifies at least one information in a meta informationstored in a managing terminal having a second terminal ID, the metainformation including plural information relating to said content; anobtaining device configured to obtain the meta information that includesthe at least one information in said retrieving condition from themanaging terminal having the second terminal ID; a specifying deviceconfigured to specify a content ID based on the meta informationobtained by the obtaining device, and configured to specify a firstterminal ID of a terminal that stores the content, the content ID beingincluded in the meta information and identifying the content; atransmitting device configured to transmit a request for obtaining thecontent relating to said content ID specified by said specifying devicethrough said network to the terminal having the first terminal IDspecified by the specifying device.